Purification of water on a household level is a necessity in order to avoid diseases in large parts of the world. In particular, in the poor part of the world, there is a large demand for a simple way to purify water on a household level, which is to be used as drinking water or the like. During crisis situations, which can occur anywhere on the earth, such as natural disasters, wars, and epidemic diseases, water purification may be extremely important in order to limit spreading of diseases, for example diarrhea diseases.
The impure water can include a number of harmful impurities, such as microorganisms in the form of pathogens. Traditionally, the water is purified from these impurities by boiling it. In poor countries, boiling of water is done over an open fire, whereby a considerable amount of wood is consumed. Approximately 1 kg wood is needed for 1 liter of water to reach 100° C. To fetch wood takes a long time and can be costly, at the same time as it has a negative effect on the environment. Here, the environment is harmed by deforestation, which results in soil erosion.
Thus, the traditional purification method has a number of disadvantages regarding environmental effects, usage possibilities and the work effort.
Other methods for purification of drinking water could be pasteurization and filtering. Pasteurization is performed by heating the water to a high temperature during a long time, which is costly. The filtering is only able to filter out microorganisms being bound to relatively large particles.
By the Swedish patent SE527988, it is already known a container for purifying water. The container includes a surface having a layer, which permeable for sunlight, and a surface, which absorbs the sunlight, where the absorbing surface has a dark color. Here, the solar radiation passes through the surface being permeable for sunlight, further through the impure water, and to the absorbing surface. The absorbing surface absorbs ultraviolet (UV) radiation and emits infrared (IR) radiation for achieving a temperature increase of the water in the container. By the use of the container, a water temperature of over 60° C. can, under favorable conditions, be obtained, after the container having been lying in sunlight for three hours. Here, a combination of filtering, heating, and UV-radiation of the water is used for reducing the number of as well as killing unwanted microorganisms, and thereby purifying the water.
However, there is a need for improving the purification of the already known container, and to make it more effective, there is especially a need for making the purification process faster and making it possible to purify a larger volume of water during a shorter time period.